Bulls N’ Bears Big Hits looks at notable drill hits recently reported to the ASX, led by Broken Hill Mines’ Centenary Zone in the Rasp mine at Broken Hill in NSW and followed by Gorilla Gold’s Sovereign Zone at Comet Vale, 100km north of Kalgoorlie and Meeka Metals’ Turnberry Mine at the company’s Murchison gold project, 50km northwest of Meekatharra. So let’s dive in.
Broken Hill Mines (ASX:BHM)
Project: Rasp mine, New South Wales
Hit: 25.8 metres at 11.7% zinc equivalent from 415.1 metres.
Broken Hill Mines has unveiled what could become a significant new silver-lead-zinc discovery beneath its flagship Rasp mine in New South Wales, after drilling intersected a broad zone of high-grade mineralisation well below the Globe-Vauxhall Shear.
The standout result from the company's first hole targeting the Centenary Zone returned 25.8 metres grading 11.7 per cent zinc equivalent from 415.1 metres, including 10.9 metres at 17.3 per cent zinc equivalent.
Management says the result was around five times wider and 27 per cent higher in grade than predicted by the existing Centenary resource model, pointing to substantial upside for the deposit.
The hole was drilled from underground platforms in the neighbouring Western Mineralisation orebody and represents the first successful test aimed below the Globe-Vauxhall Shear, a geological structure that has historically frustrated drilling efforts and resulted in limited exploration of the Centenary Zone.
Broken Hill Mines believes the intercept could signal a major reinterpretation of the geology within the area, with initial mineralogical work suggesting the newly-intersected mineralisation more closely resembles ore from Broken Hill's legendary Main Lode than the adjacent Western Mineralisation body.
The company says the discovery could represent a major step-change in the potential scale of the deposits.
The Centenary Zone currently hosts a 2024 inferred mineral resource of 4.8 million tonnes grading 9.2 per cent zinc equivalent, but the latest result suggests both tonnage and grade could be materially higher than previously estimated.
Importantly, the mineralisation sits only about 250 metres from existing underground operations, raising the prospect of a relatively low-capital development pathway if further drilling can confirm continuity.
The company has already accelerated its follow-up drilling, with multiple holes planned to test the scale of the newly interpreted mineralised trend, ahead of a proposed resource update later in the year.
Broken Hill Mines says development of the Centenary Zone could ultimately provide a high-grade bulk-tonnage feed source to complement the company's existing 750,000-tonne-per-annum processing operations at its Rasp operation.
With further assay results expected in coming weeks, keen market watchers will almost certainly be waiting closely to see whether the first hole represents an isolated high-grade intersection or the beginning of a much larger discovery beneath one of Australia's most famous mining camps.
GORILLA GOLD (ASX: GG8)
Project: Comet Vale gold project near Kalgoorlie
Hit: 9.3 metres grading 20.6 grams per tonne gold from 414.8 metres.
Gorilla Gold may have opened an entirely new chapter at its Comet Vale gold project near Kalgoorlie after drilling intersected a previously unrecognised high-grade gold lode in the footwall of its Sovereign deposit.
The discovery hole returned an impressive 9.3 metres grading 20.6 grams per tonne (g/t) gold from 414.8 metres, with the mineralisation occurring about 50m into the footwall of Sovereign's main lode system.
Notably, the company says that despite sitting within the Sovereign system, the position has never been systematically sampled or explored, raising the possibility of a sizeable new mineralised structure.
The hole was part of ongoing growth drilling within Gorilla's North Kalgoorlie Hub, which currently hosts a combined resource inventory of about 1.2 million ounces grading 3.7g/t gold across its Comet Vale and Mulwarrie projects.
The geological character of the new discovery has particularly excited management. Unlike the main Sovereign lodes, which are typically associated with quartz veining and sulphide mineralisation hosted in intrusive rocks, the new gold zone occurs within ultramafic rocks and contains virtually no quartz veining and only minor sulphides.
Gorilla Gold says the mineralisation appears tied to zones of intense deformation and may represent a completely separate style of mineralisation within the broader system. The company’s chief executive officer, Charles Hughes, said that if hadn’t been for the presence of some very coarse gold, the discovery could have been missed.
That distinction is important because the host structures and favourable stratigraphy are interpreted to extend for several kilometres along strike and at least 600m down dip, providing substantial room for future growth.
Alongside the discovery result, the company also reported a string of high-grade hits from ongoing drilling at Sovereign, including 4.2m at 13g/t gold from 360.3m and 2.3m at 14.8g/t gold from 54.3m in another hole.
Management has already commenced a resampling and follow-up diamond drilling program aimed at determining the scale of the new footwall zone, while historical holes which intersected the position are also being reviewed.
Given Comet Vale's history of producing multiple high-grade lodes extending hundreds of metres along strike and at depth, keen observers will be waiting to see if the latest hole represents the first drill intersection into another significant gold-bearing structure within the emerging North Kalgoorlie Hub.
Meeka Metals’ diamond drill core showing shearing, mineralisation and gold grades in grams per tonne (g/t) in the 493m to 500m section, part of the company’s headline 52m drill intercept from 474m depth. Credit: File
MEEKA METALS (ASX: MEK)
Project: Turnberry underground ore reserve, near Meekatharra in WA
Hit: 52.3 metres grading 3 grams per tonne gold from 474.1 metres .
Meeka Metals has strengthened the case for substantial resource growth at its Turnberry deposit, after drilling broad zones of high-grade gold well below the current underground reserve. Turnberry is part of the company’s Murchison gold project, 50 kilometres northwest of Meekatharra in WA’s Murchison region
The company announced results from a deep diamond drilling program targeting mineralisation about 200 metres beneath the existing Turnberry underground ore reserve, with multiple holes intersecting thick gold-bearing zones.
The best result came from a hole which returned 52.3 metres grading 3 grams per tonne (g/t) gold from 474.1m, including 30.6m at 3.4g/t gold and 10.5m going 3.7g/t gold.
A second hole delivered 18 metres at 3g/t gold, including 9 metres grading 5.1g/t gold, while another returned 13.8 metres at 2.4g/t gold, including 4 metres at 5.8g/t gold.
The results were generated from drilling beneath the 690,000-ounce Turnberry gold resource and well below the limits of the current mining reserves model. While the gold grades alone are impressive, management believes the accompanying geology could be equally significant.
The drilling intersected strong shearing associated with pyrite and chalcopyrite mineralisation, a combination the company says is characteristic of an intermediate level orogenic gold system likely close to a deeper, hotter and more metal-rich source.
Meeka's geological team has noted that both the width and grade of mineralisation appear to increase towards the centre of the system, suggesting the mineralised structure may strengthen at depth rather than diminish.
The company believes the new drilling demonstrates that the current resource doesn’t capture the full extent of mineralisation at Turnberry Central and could potentially support significant resource additions with further work.
A follow-up diamond drilling campaign is already under way, targeting strike and depth extensions to the strongest intersections - including the headline hit - in an effort to trace the system towards its interpreted source.
With Meeka rapidly advancing development of its broader Murchison Gold project, the company’s deep Turnberry results point to strong potential for future mine life extensions and additional high-grade feed outside the current development plan.
Keen observers will now be focused on whether the next round of drilling can confirm the presence of a significantly larger mineralised system beneath Turnberry and deliver further evidence that grades continue to strengthen with depth.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
By Doug Bright
